2. Climate and global change issues

a. Surface temperatures

Estimated global (land area only) mean
temperature anomalies during 1995 [computed using
meteorological station data received over the Global
Telecommunications System (GTS) relative to the
1951-80 base period means] were the second largest in
the historical record (0.42°C), ranking behind the
warmest year of 1990 (0.52°C), and slightly ahead of
1991 (0.41°C) and 1994 (0.41°C) (Fig. 1). This marks
a continuation of the warmer-than-normal
global-land temperatures that have been observed for the past
10 years. In addition, the four warmest years since
1951 have occurred during the decade of the 1990s.
Much of the warmth during 1995 was concentrated in
the Northern Hemisphere (Fig. 1b
), as the mean annual Southern Hemisphere temperature was only the
eleventh warmest since 1951 (Fig. 1c
).

Record warmth over land occurred during the December 1994-February 1995 (DJF) and
June-August 1995 (JJA) seasons (Figs. 2a, c). The 1994/95 DJF temperature was slightly more than +0.80°C
above normal and was larger than any seasonal departure
observed since 1951. The estimated global-land
temperatures during the March-May (MAM) and September-November (SON) seasons were also above
normal during 1995 (Figs. 2b, d
), but not at the record extremes observed during the winter and summer. This observation
contrasts with the past decade,
in which much of the anomalous warmth occurred during the first half of the year.
For example during
the last 10 years, the global DJF and MAM land
temperatures averaged more than 0.40°C above normal,
while the JJA and SON temperatures averaged near
0.25°C and 0.15°C above normal, respectively.

The estimated global mean surface temperature
for land and marine areas combined is derived from
observations at land stations and from sea surface
temperatures (SSTs) measured by ships and buoys.
The global temperature for 1995 was 0.40°C above
the 1961-90 average (Fig. 3). This anomaly exceeds
the previous warmest year in the record (1990) by 0.04°C.
The Northern Hemisphere also experienced record warmth during 1995 with temperatures
averaging 0.55°C above normal, while Southern
Hemisphere temperatures (0.23°C above normal) were not as warm as 1983 or
1987 and were about equal to 1990, 1991, and 1993.

A major contributor to the anomalous warmth during 1995 was
well-above-normal temperatures over northern Eurasia (Fig. 4). Temperatures averaged more than
3.0°C above normal over Siberia during the year, with monthly anomalies
during January and February exceeding +10.0°C across parts of this
region (see Section 4b). A time series
averaged over the countries which formerly comprised the Soviet
Union (Fig. 5) shows 1995 to be the
warmest year since 1891 for that region (+2.1°C above normal), far
surpassing the previous record anomaly of +1.4°C set in 1990.

Elsewhere, annual mean surface land temperatures were also
significantly above normal across Alaska, northwestern Canada, and Europe
(which experienced a very
warm summer, see Section 4b).
Colder-than-normal annual mean land temperatures during the year were
restricted to southern Australia and Greenland (Fig. 4).

The dissipation of warm episode (El Niño_Southern Oscillation)
conditions in early 1995 and the development of weak cold-episode
conditions by the end of the year (see Section 3) is evident in the pattern
of below-normal SSTs in the eastern equatorial Pacific (Fig. 4). However, most of the remainder of the
tropical and subtropical oceans recorded above-normal temperatures for
the year as a whole, with anomalies greater than 1.0°C covering parts
of the Atlantic Ocean (Fig. 4
). In contrast, temperatures averaged cooler than normal during 1995
throughout the North Pacific and the northern North Atlantic. Large parts of
the Southern Hemisphere oceans south of 40°S also averaged colder
than normal during 1995, especially south of New Zealand.

Regional time series for the contiguous United States (Fig. 6) and Australia (Fig. 7) show that 1995 temperatures were also above
normal in these countries (0.3°C and
0.08°C above normal, respectively). Overall, 1995 was the 20th warmest year
in the United States since 1895 and the 23rd warmest year in Australia
since 1910. In the United States, December 1994-February 1995 (DJF)
was especially warm, ranking as the 5th warmest since 1895. During this
season, one-third of the country was much warmer than normal
(upper tenth percentile), while none of the country was much colder than
normal.